High-frequency (HF) radio is in the 100- to 10-metre wavelength band, extending from 3 megahertz to 30 megahertz . Much of the HF band is allocated to mobile and fixed voice communication services requiring transmission bandwidths of less than 12 kilohertz.
Read moreWhy is VHF short range?
VHF waves, unlike longer waves, are not strongly reflected from the atmosphere; therefore, they do not bend readily around the Earth’s curvature and cannot be transmitted beyond the horizon. Their range is further limited by their inability to pass through hills or large structures .
Read moreHow is spectrum allocated in different countries?
On the basis of the requirements expressed by each country, assignment plans allocate frequencies for each station in a given service ; allotment plans grant to each country frequencies intended for use by a given service, frequencies which the country then assigns to the stations within its jurisdiction according to …
Read moreHow are allocated frequencies?
ITU definition The International Telecommunication Union defines frequency allocation as being of “a given frequency band for the purpose of its use by one or more terrestrial or space radiocommunication services or the radio astronomy service under specified conditions “.
Read moreHow is spectrum divided?
The spectrum is divided into different frequency bands, each having a specific application . For instance, the frequency band that covers 300 kHz to 535 kHz is reserved for aeronautical and maritime communications and the spectrum from 535 kHz and 1705 kHz for AM radio. This process is called “allocation”.
Read moreWhat is frequency channel spacing?
Channel spacing, also known as bandwidth, is a term used in radio frequency planning. It describes the frequency difference between adjacent allocations in a frequency plan .
Read moreWhat frequencies are used in space?
Radio frequency communications for spacecraft are conducted between 30 MHz and 60 GHz . The lower frequency bands are typically more mature for SmallSat usage, however extensive use of these bands has led to crowding and challenges acquiring licensing.
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